使用RT-Thread ping外部的主机

发布于 2014-02-27 21:32:51 浏览：2534 订阅该版

主要参考RT自带的ping 代码实现通过 RT-Thread ping外部的主机功能：
首先通过finsh串口 输入ping_start() 启动：
![启动.png](/uploads/4220_8dedb077107572411a285eb75ee79f29.png)
主要是通过lwip_socket创建套接字。里面PingSem 是为了方便测试添加的一个信号量，

ping远程主机

[attach]2207[/attach]

抓包工具数据包
![截取的数据包.png](/uploads/4220_c514f0c9c3bc26d9312d2d29a4e88583.png)

最后注意：防火墙需要关闭，或者设置一下ICMP回显，负责主机可以收到ICMP请求报文，但是不会回复。
```/*
 * netutils: ping implementation
 */

#include "lwip/opt.h"

#include "lwip/mem.h"
#include "lwip/icmp.h"
#include "lwip/netif.h"
#include "lwip/sys.h"
#include "lwip/sockets.h"
#include "lwip/inet.h"
#include "lwip/inet_chksum.h"
#include "lwip/ip.h"

/**
 * PING_DEBUG: Enable debugging for PING.
 */
#ifndef PING_DEBUG
#define PING_DEBUG     LWIP_DBG_ON
#endif

/** ping receive timeout - in milliseconds */
#define PING_RCV_TIMEO 1000
/** ping delay - in milliseconds */
#define PING_DELAY     100

/** ping identifier - must fit on a u16_t */
#ifndef PING_ID
#define PING_ID        0xAFAF
#endif

/** ping additional data size to include in the packet */
#ifndef PING_DATA_SIZE
#define PING_DATA_SIZE 32
#endif

/* ping variables */
static u16_t ping_seq_num;

struct _ip_addr
{
	rt_uint8_t addr0, addr1, addr2, addr3;
};

/** Prepare a echo ICMP request */
static void ping_prepare_echo( struct icmp_echo_hdr *iecho, u16_t len)
{
	size_t i;
	size_t data_len = len - sizeof(struct icmp_echo_hdr);

ICMPH_TYPE_SET(iecho, ICMP_ECHO);
	ICMPH_CODE_SET(iecho, 0);
	iecho->chksum = 0;
	iecho->id     = PING_ID;
	iecho->seqno  = htons(++ping_seq_num);

/* fill the additional data buffer with some data */
	for(i = 0; i < data_len; i++)
	{
		((char*)iecho) = (char)i;
	}

iecho->chksum = inet_chksum(iecho, len);
}

/* Ping using the socket ip */
static err_t ping_send(int s, struct ip_addr *addr)
{
	int err;
	struct icmp_echo_hdr *iecho;
	struct sockaddr_in to;
	size_t ping_size = sizeof(struct icmp_echo_hdr) + PING_DATA_SIZE;
	LWIP_ASSERT("ping_size is too big", ping_size <= 0xffff);

iecho = rt_malloc(ping_size);
	if (iecho == RT_NULL)
	{
		return ERR_MEM;
	}

ping_prepare_echo(iecho, (u16_t)ping_size);

to.sin_len = sizeof(to);
	to.sin_family = AF_INET;
	to.sin_addr.s_addr = addr->addr;

err = lwip_sendto(s, iecho, ping_size, 0, (struct sockaddr*)&to, sizeof(to));
	rt_free(iecho);

return (err ? ERR_OK : ERR_VAL);
}

static void ping_recv(int s)
{
	char buf[64];
	int fromlen, len;
	struct sockaddr_in from;
	struct ip_hdr *iphdr;
	struct icmp_echo_hdr *iecho;
	struct _ip_addr *addr;

while((len = lwip_recvfrom(s, buf, sizeof(buf), 0, (struct sockaddr*)&from, (socklen_t*)&fromlen)) > 0)
	{
		if (len >= (sizeof(struct ip_hdr)+sizeof(struct icmp_echo_hdr)))
		{
			addr = (struct _ip_addr *)&(from.sin_addr);
			rt_kprintf("ping: recv %d.%d.%d.%d
", addr->addr0, addr->addr1, addr->addr2, addr->addr3);

iphdr = (struct ip_hdr *)buf;
			iecho = (struct icmp_echo_hdr *)(buf+(IPH_HL(iphdr) * 4));
			if ((iecho->id == PING_ID) && (iecho->seqno == htons(ping_seq_num)))
			{
				return;
			}
			else
			{
				rt_kprintf("ping: drop
");
			}
		}
	}

if (len <= 0)
	{
		rt_kprintf("ping: timeout
");
	}
}

/* PING数据次数 */
#define PING_TIME 4

char* target;

static rt_sem_t PingSem;

void ping_thread(void* parameter)
{
	char i;
	
	int s;

/* 超时时间 */
	int timeout = PING_RCV_TIMEO;
	
	struct ip_addr ping_target;
	
	struct _ip_addr
	{
		rt_uint8_t addr0, addr1, addr2, addr3;
	} *addr;

/* 创建ping信号量 */
    PingSem = rt_sem_create("PingSem",0,RT_IPC_FLAG_FIFO);
    if ( PingSem == RT_NULL)
    {
        rt_kprintf("create PingSem failed.
");
        return;
    }
	
 	/* 等待PHY初始化完毕 */
 	rt_thread_delay(200); 
	
	/* 创建一个SOCKET连接 */
	if ((s = lwip_socket(AF_INET, SOCK_RAW, IP_PROTO_ICMP)) < 0)
	{
	    rt_kprintf("create socket failled
");
		return;
	}

/* sockopt相关选项 */
	lwip_setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout));

while (1)
	{
		/* 等待持有信号量 */
        rt_sem_take(PingSem, RT_WAITING_FOREVER);

/* PING_TIME 控制ping的次数 */
		for(i=0; i<PING_TIME; i++)
		{
			/* 首先解析地址 解析target字符串包含的地址 */
			if (inet_aton(target, (struct in_addr*)&ping_target) == 0) 
			{
				return ;
			}
			addr = (struct _ip_addr*)&ping_target;

if (ping_send(s, &ping_target) == ERR_OK)
			{
				rt_kprintf("ping: send %d.%d.%d.%d
", addr->addr0, addr->addr1, addr->addr2, addr->addr3);
				ping_recv(s);
			}
			else
			{
				rt_kprintf("ping: send %d.%d.%d.%d - error
", addr->addr0, addr->addr1, addr->addr2, addr->addr3);
			}

/* take a delay */
			rt_thread_delay(PING_DELAY); 
		}
	}
}

#ifdef RT_USING_FINSH
#include <finsh.h>

void ping_start(void)
{
	rt_thread_t init_thread;

init_thread = rt_thread_create("ping",
							   ping_thread, RT_NULL,
							   1024, 25, 20);
	if (init_thread != RT_NULL)
		rt_thread_startup(init_thread);
}

FINSH_FUNCTION_EXPORT(ping_start, ping start,);

void ping(char* url)
{
	target = url;
	rt_sem_release(PingSem);
}

FINSH_FUNCTION_EXPORT(ping, ping network host);
#endif
```
![ping.png](https://oss-club.rt-thread.org/uploads/4220_fe7299d9e4a579d8eb75fb53a11abce3.png)